Controller for electric motors.



WITNESSES J. H. HALL.

CONTROLLER FOB ELECTRIC MOTORS.

APPLICATION FILED DEO.13,191L

Patented May 19, 191i AAAIAA lIllll "vi NV INVEN TOR.

A ZTORNE Y.

JAY H. HALL, OF CLEVELAND,

MANUFACTURING COMPANY, OF CLEVELAND, OHIO,

A. CORPORATION OF OHIO.

conrnonnna roa nnnc'rmc MOTORS.

Specification of Letters fatent. Patented Ma 19 9 1914 Application filed December 13, 1912. Serial N 0. 736,529.

To all whom it may concern:

Be it known that I, JAY H. HALL, a citizen of the United States, residing at Cleve land, in the county of Cuyahoga and State of Ohio, haveinvented new and useful Improvements in Controllers for Electric-M0- tors, of which the following is a-- specification.

My invention relates to the control of electric motors, and particularly to the control of alternating current motors in which a transformer, or voltage-reducing device, is used for starting a motor.

One of the objects of my invention is to provide a controller which, after the motor has been started, automatically disconnects it from the transformer and connects it directly to the source of supply.

Other objects will appear hereinafter as described.

In working out myinvention, I preferably use a current-limit relay which controls the operation of the controller in disconnecting the motor from the transformer and connecting it to the source of supply in accordance with the amount of current flowing in the motor circuit.

The accompanying drawing is a diagrammatic representation embodying my invention as adapted for the control of an alternating current induction motor.-

The induction motor is shown at 1, arranged to be supplied with current from the source of supply 3, 1, and 5.

For starting the motor, I employ a transformer with the windings (5 and 7, the common point of which is connected to the middle terminal of a three-pole main switch 8. One terminal of the motor is also connected to this terminal of the switch. The remaining terminals of the transformer windings are connected through the normally closed switches 10 and 12 to the remaining terminals of the switch 8. The remaining terminals of the motor are connected through the normally closed contacts 9 and 11 to taps on the transformer windings.-

To effect the movement of the contacts 9, 10,11, and 12,1 employ a magnetically-operated switch with winding 19, which, when sufficiently energized, will draw in its plun ger and cause the arms connected thereto to engage the contacts 9, 10, 11, and 12, and separate them from their coiiperating con tacts '13, 11, 15, and 16. The arms 17 and 18 make electrical contact with the movable contacts 9 and 11. When the winding 19 is denergrzed, the spring T retracts the plunger and the arms connected thereto, allowmg the contacts 9, 10, 11, and -12 to be closed by their respective springs S.

OHIO, assronon TO mic ELECTRIC conrnonnnn' AND 9 The resistance 22 in the circuit of the i winding 19 is such that the winding is not sufiiciently energized to close its switch,

when the resistance 22 is inserted in series with the winding, but after the switch is once closed the resistance 22 can be inserted in series with the winding 19 without causing the switch to open. In order to short circnitthe resistance 22 and allow the winding 19 to operate the switch to disconnect the motor from thetransformer and connect it directly to the source of supply, I provide the relay 20 which has its winding 21 connected in, the motor circuit when it is connected to the transformer. 1 Thisrelay is of the type shown in Eastwoods Patent, No. 1,040,292, which has the peculiar characteristic of remaining in its normal or open position when its winding is excited with a current above a certain value, and of operating to close its contacts when the current in the winding is reduced.

The operation of the controller is as follows: To start the motor the'operator closes the hand-operated switch 8. Current now .flows from the source of supply to the transformer windings, and through these windings to the motor. The first rush of current taken by the motor in starting will be suflicient to lock the relay in its open position as shown in the drawings; but as the motor comes up to speed the current in the winding 21 is diminished, and when it has reached the value to which the relay is adjusted to close its contacts, the relay will operate and short circuit the resistance 22, which has previously been in series with the winding 19 and prevented the winding from pulling in its plunger. As soon as the relay closes its contacts and short circuits the resistance 22, the winding 19 pulls in its plunger and iltl , the contacts of -cuit breaker to open the '34 in the circuit of switch to open. If

switch 8 and with the source of supply. Since the circuit through the winding 21 of the relay is now opened at the contacts 12, the relay opens its contacts and reinserts the resistance 22 in series with the winding 19, but suficient current still flows in the winding 19 to hold the switch in its operated position. The motor, now bein connected directly to the source of supp y, runs at its normal speed. The motor may be stopped at any time by opening of the switch 8. At the instant the movable arms 17 and 18 engage the contacts Q'and 11, a portion of the transformer windings 6 and 7 are momentarily short-circuited, and to prevent any serious arcing at the contacts 13 and 15, resistances It and R may be inserted these contacts, if found desirable.

I have shown the winding 21 of the relay 20 connected in the circuit which supplies current to the transformer through the'contacts 16. It is obvious that the winding 21 can be connected in any of the circuits which carry the motor current while the motor is being started. It could be connected, for instance, in tho'circuit which passes through the contacts 13, 14, or 15, or it could be placed in one of the circuits which carries the motor current both in startingnnd in running. In the latter case it would not open its contacts when the motor is disconnected from the transformer and connected directly to the source of'supply, and the resistance 22 may be omitted.

I have shown at 30 a magnetically operated circuit breaker which disconnects the motor from, the source of supply in case an overload occurs in the motor circuit. If too great a current flows, the winding of the overload device 32 will cause the opening of this device, therey deenergizing the winding 31 and allowing the cirsupply circuit. The circuit breaker winding 31 may be connected to the source of supply through the contacts 330i a reset switch in the power house, by which the attendant may reset the circuit breaker after. an overload has occurred, causing it to open. To cause the circuit breaker to close, the attendant closes the contact 33, short-circuiting the resistance the winding 31. When the resistance 34 is short-circuited, suflicient current flows in the winding 31 to cause the switch 30 to close its contacts, and the resistance 34 can then be reinserted in the ,circuit' of the winding without causing the at the power house wishes to open the circult breaker 30, he

may do so in opening the switch 35, thereby cutting off the current of the circuit breaker winding 31.

I have used the term transformer to mean an into-transformer, choking coils. or other voltage reducing devices.

in series with.

If it is not desired to disconnect the transformer from the source of supply when the motor is running, the contacts 10 and 12 and their cotiperating contacts 14 and 16, together with the movable arms 17 and 18 may be omitted. In this case it may be desirable to connect the winding 21 of the relay in the circuit through the contacts 13 or 15, although it is not necessary to do so.

I claim 1 1. In combination, an induction motor, a supply circuit, a transformer, means for connecting the transformer to the supply circuit, a single switch mechanism containing a set of contacts for disconnecting the motpr' from the transformer and for connecting' it to the supply circuit, and a winding for operating the said switch mechanism. 4

2. In combination, an induction motor, a supply circuit, a transformer, means for connecting the motor to the supply circuit through the transformer, a single switch mechanism containing a set of contacts for disconnecting the motor from the transformer, for disconnecting the transformer from the supply circuit, and for connecting the motor to the supply circuit, and a winding for operating the said switch mechanism.

3. In combination, an induction motor, a supply circuit, a transformer, means for connecting the motor to the supply circuit through the transformer, a single switch mechanism having contacts operated by a single winding to disconnect the transformer from the motor and the supply circuit and to connect the motor to the said supply circuit, and a current-limit relay for controlling the operation of said switch mechanism.

tion motor, a source of supply, a transformer, normally closed contacts in the circuits connecting the transformer to the motor, normally open contacts in the circuits connecting the motor to the source, and a winding for operating the said contacts.

at any time the attendant 5. In a motor control system, an induction motor, a source of supply, a transformer, normally closed contacts in the circuits connecting the transformer to the motor, normally open contacts in the circuits connecting the motor to the source, and means for operating the said contacts when the current-in the motor has decreased to a certain value.

6. In combination, an alternating currentmotor, a source of supply, a transformer, a

main switch connecting the source to the.

transformer, normally closed contacts between the transformer and said main switch, normally closed contacts connecting the motor to'the transformer, normally open contacts for connecting the motor to the source 4:- Ina motor control system, an induc- I through the said main switch, and a winding for operating the said normally closed and normally open contacts.

7 In combination, an alternating current motor, a source of supply, a trans ormer, a main switch connecting the source'to the transformer, normally closed contacts between the transformer and said main switch, normally closed contacts connecting the motor to the transformer, normally open con i tacts for connecting the motor to the source through the said main switch, a winding for operating the said normally closed and normally open contacts, and a current limit relay for controlling said winding.

8. In a motor control system, an alternating current motor, a source of supply, a transformer, normally closed contacts connecting the transformer to the motor and to the said source, normally open contacts for connecting the motor to the said source, a winding for opening the normally closed contacts and closing the normally open contacts, a relay for controlling saidwind: ing having normally open contacts in series with the winding, and an operating wind-- ingfor the relay energized by current in the motor circuit. 7

9. In a motor control system, an alternating cu'rrent.motor, a source of supply, a transformer, normally closed contacts connecting the transformer to the motor and to the said source, normally open contacts for connecting the motor to the said source, a winding for opening the normally closed contacts and closing the normally open contacts, and means for preventing the operation of the contacts until the current in the motor circuit is below a predetermined value.

10. In a motor control system, an alternatin current motor, a supply circuit, a trans ormer connected thereto, means connecting the motor to the transformer, means, for connecting the motor to the supply circuit, and means controlling the change of former t0 the supply circuit, said means comprising a relay with normallyopen contacts and a winding for operating the contacts when the current through the motor isbelow a predetermined value.

Signed at Cleveland, Ohio, this 11th day of December, A; D1912.

JAY H. HALL.

Witnesses:

HARRY R. GANFIELD, H. M. Dm-MER.

connection of the motor from the trans- 

